Exploring the Physics of Ferrimagnets for Future Spintronics Applications

Spintronics is a field that addresses science and engineering at the intersection of magnetism and transport phenomena in small structures and devices. By focusing on the electron’s spin rather than its charge, spintronics enables faster and more energy-efficient information and communication technologies.

Ferrimagnetic materials stand out among the spintronics community. Discovered in 1948 by Louis Néel, ferrimagnetism occurs when a material is composed of atoms with opposing magnetic moments of unequal magnitude, resulting in net spontaneous magnetization. Ferrimagnetic materials are attractive because they combine the controllability of ferromagnets with the fast dynamics of antiferromagnets.

The latest Special Topics edition of the Journal of the Physical Society of Japan presents articles covering a broad spectrum of spintronics research on ferrimagnetic materials.

On the theoretical side, Barker and Atxitia review computer modelling and simulation techniques for the magnetic excitations of complex magnets at finite temperatures. Nakata and Kim review a formalism for spin transport in ferrimagnets involving the topological Hall effect.

On the experimental side, Nambu and Shamoto study single crystals of yttrium iron garnet using polarized and unpolarized inelastic neutron scattering, giving unprecedented insights into the collective precessional motion called spin waves or magnons in this complex material.

Chudo and coworkers focus on the angular momentum compensation temperature measured via nuclear magnetic resonance and the Barnett effect, which is the magnetization induced by mechanical rotation.

Sheng and coworkers report the generation of fast and chiral spin waves in yttrium iron-garnet nanostructures by microwaves and electric currents.

Zhou and coworkers focus on the current-induced fast magnetization dynamics near the magnetic compensation point of both insulating and conducting ferromagnets that enable fast domain wall motion.

Avci emphasizes the electrical control of magnetic excitations in ferrimagnetic insulators by heavy metal contacts.

Stupakiewicz and Satoh discuss the ultrafast magneto–optical response of ferrimagnetic insulators, while Iihama and coworkers discuss the optical magnetization switching in magnetic metals close to compensation.

Suemasu and coworkers report progress in the fabrication of rare-earth free ferrimagnetic manganese nitride films.

Tanabe and Ohe report enhanced electric voltages induced by magnetization dynamics in nearly compensated ferrimagnetic gadolinium–iron–cobalt alloys.

The impressive progress reported by the global research community in this special issue raises the hope that ferrimagnet-based spintronics will contribute to a sustainable information society for the benefit of all mankind.